Hello everyoneBefore asking the question, I want to tell you that I'm a 10th grade Vietnamese student, so I'm not sure whether I use the correct English or not. But I'll try to make it as clear as possible.So, here's the question: "In pinocytosis, how can cells choose which substance is necessary for them, when there are many other subtances around, to take in?"It's a question in my textbook. But I've read on Wiki that cells take in every substance around them in pinocytosis, which means they don't have to choose. So I'm very confused.Please help me, I can wait for the answer because this question is for Biological special class so I don't have to do it (I'm in the ordinary class :"> I've asked my friend who is a student in that special class but she said she didn't know). But I still want to know the answer.Again, sorry for the bad English

@JackBean: Thank you ^^ So you mean that the receptors will know if a substance is unnecessary, and they won't allow it to come in?And... um... did I use the right English? Did I make any mistake in spelling or grammar or something? :">

Pinocytosis is a type of endocitosis. Endocytosis can be FAGOCYTOSIS (when cell "EAT" something) and PINOCYTOSIS (when cell "DRINK" something) - when cell is taking needed substances with a 'fluid drop'. And, visualy, you can recognize it by long, very thin invagination.

'Right, Jack. And I don't know why I wrote that ( endocytosis) earlier. A bit tired this morning ! It's "Receptor-Mediated Endocytosis". That process.

So what the thread author asked is how the cell, in pinocytosis, differentiates the stuff it needs from what it does not. And it seems that description best suits "Receptor-Mediated Endocytosis".

In pinocytosis, how can cells choose which substance is necessary for them, when there are many other subtances around, to take in?"It's a question in my textbook. But I've read on Wiki that cells take in every substance around them in pinocytosis, which means they don't have to choose. So I'm very confused.

JackBean wrote:Why should be textbook confusing? The answer is simply that it doesn't choose.

Jack, it could be considered misleading. In the question, there is what seems to be a premise, given.

In pinocytosis, how can cells choose...

So the correct answer1/ would be similar to what you answered, ( but a bit more explicit as to the circumstance involved , which is "during pinocytosis"), to reply to the query words "cell" and "can choose"

2/ would reflect ( would be a literal answer to ) "how it can" .

Therefore, a problem arises; although the "truth" is revealed in reply to part (1/); "during pinocytosis the cellcannot choose..." , that answer does not respond to part (2/), which is response to "how".